Insect cells are widely known as hosts for baculovirus expression vectors (BEVs), which can produce large amounts of recombinant proteins with eukaryotic modifications. The insect cell-BEV system has been used to produce many different recombinant proteins, facilitating biomedical research on their structures, functions, and roles in disease. Many companies are using the insect cell-BEV system to produce recombinant proteins for high-throughput functional screens and to develop vaccines, therapeutics, and diagnostic reagents. The advantages of using insect cells for these applications include ease of scale-up, lower costs, and the absence of human adventitious agents. These important research activities require a dear understanding of protein biosynthesis and processing pathways in insect cells. However, this has not been a major topic of research. This proposal focuses on the insect cell protein N-glycosylation pathway. The long-term goals are to provide an unequivocal and detailed view of this important metabolic pathway in insect cells and to use this knowledge to develop new insect-based protein production systems with more extensive recombinant glycoprotein processing capabilities. The widespread use of insect cells as protein production systems for many important biomedical research projects is a strong justification for this research. Intelligent use of insect cells for recombinant glycoprotein production will require a better understanding of their N-glycosylation pathway. This understanding can direct innovative metabolic engineering efforts to produce new insect ceft-BEV systems with improved N-glycoprotein processing capabilities. Insect cells also occupy an important niche as models for fundamental research in the emerging field of glycobiology. The insect cell N-glycosylation pathway lies in-between the pathways of lower and higher eukaryotes in complexity. Thus, well-defined differences in insect protein glycosylation pathways could be exploited as specific targets to develop future insecticides. This could lead to better ways to control agriculturally and medically important insects and the diseases they help to spread, which would have a major impact on public health, worldwide.